Gas sensor

Abstract

A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to PCT application PCT / US2010 / 032990, filed Apr. 29, 2010, which claims priority to U.S. Provisional Application Ser. No. 61 / 175,367 filed May 4, 2009, entitled Gas Sensor, Andreas K. Schmid, et al. inventors, the contents of which provisional application is incorporated herein as if fully set out in its entirety.STATEMENT OF GOVERNMENTAL SUPPORT[0002]The invention described and claimed herein was made in part utilizing funds supplied by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The government has certain rights in this invention.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]This invention relates generally to gas sensors, and, more specifically to miniaturized sensors for the detection of very low levels of ambient gases, especially hydrogen.[0005]2. Background Prior Art[0006]There are analytical tools today which are capable of qualitatively and quantitatively ...

AI Technical Summary

Benefits of technology

The patent describes a new discovery that certain materials can switch their easy axis of magnetization when exposed to gases like hydrogen. This discovery has been used to create a gas sensor that measures the resistance of a multilayered sensor stack, which changes when hydrogen is present or not. The sensor can be combined with a heating element to allow for repeated measurements, and the resistance can be used to compute gas concentrations. The sensor structure can be incorporated into a circuit board with programmable heater power, resistance measurement, and process control to identify the gas detected. The patent provides a novel way to detect gases using a simple and effective mechanism.

Problems solved by technology

These include relatively expensive and large laboratory tools with sensitivity for spectroscopic analysis of a broad range of gas compositions (example: the quadrupole mass spectrometer), as well as miniaturized sensors that are optimized for the detection of the concentration of a particular type of gas molecule (example: an oxygen sensor in automobile emission control systems).

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